Process for improving paper and product



United States Patent 2,712,994 PRGCESS F93 G PAPER AND PRODUCT George E.Niles, Winchester, Mass, assignor to Monsanto Chemical Company, St.Louis, Mo., a corporation of Delaware No Drawing. Application January27, 1949, Serial No. 73,217

9 Claims. (Cl. 92-3) The present invention relates to processes forimproving the rewetting properties or water-absorbency of paper andparticularly paper towelings and to the paper so produced.

It is one object of the present invention to produce paper towelingswhich have improved rewetting properties.

Still further objects and advantages of this invention will be obtainedfrom the following description and the appended claims.

The present invention is carried out, in general, by

adding a small amount of a Water-soluble or water dis- T persiblereaction product of tall oil and ethylene oxide to a water slurry ofpaper pulp at some stage before the pulp is formed into a wet sheet onthe wire and then finishing the paper in the normal way. Thus, the talloil-ethylene oxide reaction products may be added to the paper pulp atthe beater or the machine chest or even at the head box in the normalpaper manufacturing equipment, after which, the paper is formed on thewire in the usual manner and dried. The paper pulp may also containother additives, that is wet strength resins, alum, softening agents andthe like.

Reaction products of tall oil and ethylene oxide suitable for use inthis invention are prepared, for example, by condensing 100 parts byweight of tall oil with about 100 parts by weight of ethylene oxide. Itis also possible in some instances depending upon the wood pulp used, toemploy reaction products prepared by condensing 100 parts by weight oftall oil with 50 parts by weight of ethylene oxide. By increasing theamount of ethylene oxide reacted with tall oil, it is possible toincrease the rewetting properties of the finished paper to some extent.Thus, excellent results have been obtained by using the reaction productof 100 parts by weight of tall oil and about 210 parts by weight ofethylene oxide. In preparing the reaction products used in thisinvention, it is possible to replace a part or all of the tall oil withrosin oils obtained by the destructive distillation of colophony orrosin and/or with rosin acids. Rosin oils and acids, however, are not assatisfactory as tall oil and the latter is preferred.

The reaction or condensation of tall oil with ethylene oxide is suitablycarried out in a closed vessel such as an autoclave at elevatedtemperatures, usually above 100 C. and in the presence of a small amountof alkali as a catalyst, say about 3% by Weight of the charge ofpotassium hydroxide.

The amount of reaction product of tall oil-ethylene oxide employed maybe varied to some extent, but should be sufficient to improve therewetting properties of the finished paper. Excellent results have beenobtained in accordance with the present invention by using from about0.2 to 0.5% by weight of such reaction product based on weight of drypulp and these amounts are preferred. However, larger amounts may beused if desired. Amounts less than 0.2% by weight may be used in certaininstances depending upon the paper pulp employed and the effect desired.

The process described herein may be used to improve the rewettingproperties of a large variety of papers, that is, papers produced fromvarious types of wood pulps such as bleached and unbleached kraft,bleached and unbleached sulfite, bleached and unbleached ground woodpulp and the like, and mixtures of such pulps or mixtures of such pulpswith bleached or unbleached soda pulp.

By treating paper pulp in the manner described and then forming it intoa Wet sheet and drying, it is possible to obtain paper towelings havingexcellent rewetting properties at low cost. The improvement obtained isparticularly noticeable in the case of pulps which are also treated withalum. Thus, alum normally tends to impart a certain degree of waterrepellency to paper.

- When alum is employed together with the reaction products describedherein, it is still possible to prepare paper towelings having excellentrewetting properties, that is, the ability to take up water rapidly anduniformly.

A further understanding of the present invention will be obtained fromthe following examples which are in tended to be illustrative of theinvention, parts and percentages being by weight unless otherwisespecified.

Example I A wood pulp furnish of bleached sulfite pulp and 65% bleachedsoda pulp was beaten to 500 cc. TAPPI (Technical Association of the Pulpand Paper Industries) freeness. To this was added 0.2%, based on the drypulp weight, of the reaction product of 100 parts of tall oil and 140parts of ethylene oxide. This pulp slush was divided into two equalparts one containing 1% alum and the other containing no alum. Thesamples were then made into paper on a Noble-Wood Laboratory Sheetmachine and had a basis weight of 43 pounds per ream (500 sheets, 25inches x inches). The dried paper was tested for absorbency essentiallyas per TAPPI standard T-432 M- except that 0.05 cc. of testing water wasused instead of the usual 0.1 cc. The number of seconds for the paper tocompletely absorb the 0.05 cc. of water was determined. The lower thevalue the better the rewettiug properties or water-absorbency of thepaper is.

The following table indicates the values obtainedas compared to a blank,that is, a paper made in the same way but not treated with the abovedescribed reaction product:

0.2% sulfonated castor oil, which is a prior art rewetting agent, wastested in the same manner with the following result:

N o Alum 1% Alum Secs. Secs.

Paper treated with sulfonated castor oil 12 Example 11 Papers wereprepared in the same manner as described in Example 1 except that 0.5%of the reaction product of parts of tall oil and parts of ethylene oxidewas used based on the dry pulp weight. A similar paper was preparedwithout such reaction product and one was prepared which was treatedwith 0.5% sulfonated castor oil. The papers were then tested forwater-absorbency in accordance with the test procedure described in Ex-Example'IIl A food pulp furnish of very hard to rewet bleached sulfitepulp was refined to 500 cc. TAPPI freeness. To portions of this furnishwere added 0.2 and 0.5%, based on the dry pulp weight, of the reactionproduct of 100 parts of tall oil and 140 parts of ethylene oxide.Similar furnishes were prepared using 0.2 and 0.5%, based onthe dry pulpWeight, of sulfonated castor oil, and other furnishes were prepared in asimilar manner, but without rewetting agent additives, for comparison.Portions of these furnishes were treated with 1% alum and other portionswere not treated with alum. The water-absorbency test was made inaccordance with the procedure referred to in Example 1.

The following table illustrates the comparative 'efi'ectiveness of therewetting agents tested: 7

No Alum 1% Alum Secs.

Secs.

(a) Blank .L.. Paper treated with 0.2% of tall oil-ethylene oxidereaction product 56 86 (0) Paper treated with 0.5% of tall oil-ethyleneoxide reaction product 56 62 (d) Pager treated with 0.2% sulfonatedcastor 69 230 o (2) Paper treated with 0.5% sulfonated castor oil 64 262Example IV Paper sheets were prepared as described in Example III exceptthat unbleached kraft pulp was employed instead of bleached sulfitepulp. The following table illustrates the comparative rewettingproperties 'ofthe differently treated papers:

No Alum 1% Alum Secs.

(a) Blank (b) Paper treated with 0.2% tall oil-ethylene oxide reactionproduct (100:140 (0) Paper treated with 0.5% tall oil-ethylene oxidereaction product (100:140) 32 38 (d) Papler treated with 0.2%sulfonatedcastor o -i e Pa or trea ed with 0.5 sulfouaed caster 9 a .1. .7? .5 64102 The tall" oil employed in preparing the reaction products used inthis invention may be crude tall oil obtained by vacuum distillation ofpulp black liquor skimmings or it may be semi-refined, that is, furtherpurified to remove unsaponifiable impurities and to improve the color.Tall oils generally contain between about to by weight of rosin acidsincluding abietic acid.

and about to 40% by weight of unsaturated fatty acid including -linoleicand olcic acids, the remainder con sisting of impurities andunsaponifiable materials.

What is claimed is: 1. A method of preparing paper toweling having highwater-absorbency properties which consists in incorporating alum and awaterdispersible reaction product of (1) 100 parts by weight of amaterial selected from the group consisting of tall oil, rosin oils,rosin acids and mixtures thereof and (2) from about 50 to 210 parts by.weight of ethylene oxide, in a water slurry of paper-forming wood pulp,said reaction product being-employed in amounts of about 0.2 to 0.5% 'byweight, based on the dry pulp weight, thereafter forming a wet iii sheetof paper toweling from the resulting slurry and then drying said sheet.

2. A method of preparing paper toweling having high water-absorbencyproperties which consists in incorporating alum and the reaction productof parts by weight of 'tall oil with about 100 to 210 parts by weight ofethylene oxide in a water slurry of paper-forming wood pulp, said alumbeing employed in an amount of 1% by weight based on the slurry, andsaid reaction product being employed in an amount of about 0.2 to 0.5%by weight, based on the dry pulp weight, thereafter forming a wet sheetof paper toweling from the resulting slurry and then drying said sheet.

3. Paper toweling composed of wood pulp fibers having incorporatedtherein alum and from about 0.2 to 0.5% by Weight, based on the dry pulpin the toweling, of a waterdispersible reaction product of'(1) 100 partsby weight of a material selected from the group consisting of tall oil,rosin oils, rosin acids and mixtures thereof and (2) from about 50 to210 parts by weight of ethylene oxide.

4. Paper toweling composed of wood pulp fibershave ing incorporatedtherein 1% by weight of alum, a wet. f

strength resin and from about 0.2 to 0.5% by weight,

based on the dry pulp in the toweling, of a reaction product of 100parts by weight of tall oil with about 100 to 210 parts by weight ofethylene oxide.

5. A method as in claim 1, but further characterized in that a wetstrength resin is also present in the water slurry of the wood pulp.

6. A'method as in claim 1, but further characterized in that the woodpulp consists of sulfite wood pulp.

7. A paper toweling as in claim 3, but further characterized in that thewood pulp consists of sulfite wood pulp.

8. A paper toweling as in claim 3, but further characterized in that thewood pulp consists of kraft wood pulp.

9. A paper toweling as in claim 3, but further characterized in that thewood pulp consists of ground wood pulp.

References Cited in the file of this patent UNITED STATES PATENTS1,370,650 Hoskins Mar. 8, 1921 1,624,599 Hilton Apr. 12,927 1,821,856Spafford Sept. 1, 1931 1,958,202 Novak May 8, 1934- 1,970,578Schoelleret al. Aug. 21, 1934 2,005,397 Schur June 18, 1935 2,178,831Bruson Nov. 7, 1939 2,183,711 DeWitt Dec. 19, 1939 2,285,366 She'fiieldJune 2, 1942 2,308,763 Little Jan. 19, 1943 2,316,120 MacLaurin Apr. 6,1943 2,338,602 Schur Jan. 4, 1944 2,376,687 'Goldstein et al. May 22,1945 2,376,688 Goldstein et al. May 22, 1945 2,380,043 Hochwalt July 10,1945 2,387,429 Cate Oct. 23, 1945 2,418,820 Coggins et al. Apr. 15, 19472,469,493 Barker May 10, 1949 2,626,213 Novak Jan. 20, 1953 FOREIGNPATENTS 790,198 France May 17, 1935 OTHER REFERENCES Kinney, Paper Ind.& Paper World, April 1942; pp. 50-51.

37-41 and 46.

3. PAPER TOWELING COMPOSED OF WOOD PULP FIBERS HAVING INCORPORATEDTHEREIN ALUM AND FROM ABOUT 0.2 TO 0.5% BY WEIGHT, BASE ON THE DRY PULPIN THE TOWELING, OF A WATER-DISPERSIBLE REACTION PRODUCT OF (1) 100PARTS BY WEIGHT OF A MATERIAL SELECTED FROM THE GROUP CONSISTING OF TALLOIL, ROSING OILS, ROSIN ACIDS AND MIXTURES THEREOF AND (2) FROM ABOUT 50TO 210 PARTS BY WEIGHT OF ETHYLENE OXIDE.